For Work Package 5, we successfully conducted fieldwork during two extensive sampling campaigns. During these campaigns, we retrieved two lake sediment cores and 22 riverine sediment samples. In addition, aerial imagery from archives was obtained.

For the sediment cores, we are in the process of performing several analyses to capture landscape changes in terms of climate, vegetation, animals, and land use. To achieve this, we subsampled a range of proxies such as sedimentary ancient DNA, pollen, and phytolith, which will all inform past vegetation, animals and land use on different spatial scales. Furthermore, XRF scans were conducted of the sediment cores, to observe changes in the past influx of different elements, which informs us on past rainfall intensity. These analyses are combined with radiocarbon dating to establish the ages of both sediment cores. Luminescence dating of the sediment cores will add to the certainty of the ages we obtained from the radiocarbon dating.

Figure 1: Sediment sorting of the riverine samples

The aim is to understand the past depositional environment in and around Bardia National Park, and to identify when transitions in the river landscape occurred. Grain sizes of the 22 riverine samples were also analyzed. The results will feed into the knowledge of constructing the past river system.

Additionally, field observations such as small-scale topography, sub-surface augering and aerial imagery measurements of the lakes were combined with electrical conductivity measurements of various water sources in and around the lake. Based on these data, a conceptual lake evolution model was developed by Master student Roan Hick.

Figures 2-4: Sediment sorting, Luminescence sampling and electrical conductivity measuring

Fieldwork conducted in late 2023 has begun to yield results. Sedimentary ancient DNA was successfully extracted from our sampling sites, and pollen and phytolith counts align with the DNA data, confirming the robustness of our findings. These results were presented at the 2nd SedaDNA Society Conference (June 2025).

Additional fieldwork in winter/spring 2025 included vegetation plot surveys, which further validated the pollen/phytolith/DNA results, and the collection of soil cores at Lamkauli Phanta to investigate the timing and development of these landscapes.

Dating of sediment cores and geomorphological samples is progressing. While initial challenges arose, a combined approach using bulk radiocarbon, charcoal radiocarbon, and luminescence dating now provides reliable ages.

Preliminary findings indicate sediments up to ~1500 years old, enabling landscape reconstructions at this time scale. The detailed insights from sedimentary ancient DNA on vegetation transitions will provide valuable input for future conservation decisions, particularly if we can confirm the presence of past wild bovine species. Likewise, understanding how and when the Madhuvan oxbow developed will yield important implications—not only for water management around the park but also for other work packages (notably WP4 and WP6).

In addition to the landscape reconstruction, we plan to share sedaDNA results on Gaur presence with the DNPWC and NTNC to help establish a baseline for conservation practices. Moreover, ongoing analyses suggest that we may be able to provide a detailed overview of landscape history, which could also be of interest to local stakeholders — for example, in the context of ecotourism.